Practicing a musical instrument is usually associated with professional supervision and personalized feedback when it comes to an unskilled apprentice. This is particularly true for a novice. Otherwise, fatigue may set in quickly, and even the most talented student can lose interest in continuing with practice or even in learning music as such. But yet, not everybody is willing to pay a personal tutor, especially if the outcome is unclear. Other factors, such as dispensability, can also influence one's decision. A reasonable compromise may consist in learning agents that take the role of the tutor. And to avoid further spendings on expensive hardware, the agents would preferably be installed on a tablet computer, which as of today is equipped with a speaker and a microphone.
Practicing, e.g., the jazz guitar, one of the main obstacles one would surely encounter from a signal processing point of view is the isolation of the solo from the recording, which as a rule contains the solo and the accompaniment. The latter is generated by the computer and can be deemed known. Thus, the challenging nature of the task stems from the fact that the accompaniment signal is altered by the speaker, the acoustic channel, and the microphone. Furthermore, the high spectral dynamics of musical signals and their high bandwidth render the task problematic for classic solutions.